In the context of the present invention a distinction is drawn between intracardial electrode lines on the one hand and intravascular electrode lines on the other hand, in the sense that intracardial electrode lines are designed in such a way that their sensing or stimulation electrodes are placed after implantation in the atrium or ventricle of a heart while intravascular electrode lines, in the narrower sense used herein, are those electrode lines whose electrodes are disposed after the implantation operation in a blood vessel such as for example a vein or an artery. By virtue of the spatial restriction which prevails in such blood vessels the corresponding intravascular implantation locations are more difficult to aim for than intracardial implantation locations. In addition the intravascular implantation locations vary from one patient to another to a greater degree than is the case with intracardial implantation locations.
In connection with the stimulation of a heart, stimulation of the left part of the heart represents a problem for the reason that placement of intracardial electrodes in the left heart is highly complicated and expensive. Therefore, instead, to stimulate the left atrium or ventricle, use is made of intravascular electrodes which are introduced for example into coronary blood vessels. That gives rise to the problem referred to in the preceding paragraph.